Accounts Receivable - Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contract receivables	$ 55,108	$ 72,835
Allowance for doubtful accounts	(2,181)	(1,749)
Accounts receivable, Total	66,131	83,062
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 13,204	$ 11,976